Why MUST you replace your stereo?
I live outside of Philadelphia, and havent done much testing of HD down the shore...
But HD is available on most stations, and depending upon the content provided, can be pretty good.
For example, our oldies station has two HD stations, one is always 70s music, the other is sports, local programming, etc. At Christmas, the HD2 station plays Christmas music all the time.
Other stations like our classic rock station just play alternate classic rock music, sometimes they claim it is "deep tracks".
For now there are no commercials on any station but the HD1, which is the same as commercial analog FM.
I only have HD in my new BMW, which has exceptional sound and the hi-fi system. I can't say if it is CD quality, like I believe is claimed... HD does NOT stand for high definition or anything like that. It is marketing misrepresentation, as they used HD which has a standard set of definitions in A/V, instead as "hybrid digital" audio. What I will say is that it DOES sound better than FM audio, there is a discernible difference in detail level that can be heard if your sound system is up to the task.
It seems to me that depending upon the station, it can take longer or shorter to latch onto the HD signal, even if you are nearby. I dont know the actual range of HD, but monmouth county has a pretty open and straight path over water from NYC, so Id think the signal should travel...
Since I live and drive mostly within 20 miles of the Philadelphia towers, HD is a no brainer. Id say that based upon what Ive read about it, you should look for a HU that has the option to turn off HD acquisition so it doesnt switch in and out all the time, if your signals are more on the fringe. Id guess that all HD analog FM tuners are more or less as good as any others in standard consumer equipment...